1. Field of the Invention
The invention relates to the conditioning of material such as tobacco wherein a gaseous medium such as air is directed onto the material. The invention has particular utility in providing for uniform drying, cooling or moisture addition with respect to the material.
2. Description of Prior Art
It is known that material such as tobacco being processed may be conditioned by heating, cooling, adding moisture content and other processing operations. The Wochnowski U.S. Pat. Nos. 3,502,085 and 3,556,111 relate to apparatus for the conditioning of tobacco wherein heated air is directed onto the tobacco during processing. Wochnowski provides a heating chamber including a plate-like sieve or distributor for the purpose of distributing heated air from the heater uniformly in all zones of the tobacco to insure uniform heating and control expulsion of nitrogen. The structure of the sieve disclosed therein is understood as comprising a plate defining a plurality of openings. Other present-day techniques in conditioning tobacco directs a heated air stream off a baffle onto a conveyor carrying the tobacco. These prior art techniques of directing the air stream produce wide variations from point to point and time to time in the airflow velocity which exists across the conveyor. The end result of these variations in airflow velocity are variations in drying.
Various devices for directing air to a particular area are known. Freeman U.S. Pat. No. 3,579,849, for example, discloses a jet tube for the purpose of expelling air vertically and keeping it away from the ends of the chamber. The purpose of the jet tube is to direct the air across a horizontal area. The Schlemmer U.S. Pat. No. 3,455,120 relates to controlling airflow utilizing a plurality of channels through which the air is directed in order to distribute the airflow. Howell U.S. Pat. No. 3,848,465 relates to an anemometer with a honeycomb structure in the airflow path. It appears that the function of the honeycomb structure in this instance is to change direction of airflow, the patent stating at Col. 4 beginning at line 15 that "the air emerges from the honeycomb with no horizontal momentum therein." Honeycomb material is also commonly used as a flow straightener in wind tunnels.